CN103209593B - The method of dry seed - Google Patents

Abstract

The present invention relates to the method adopting zeolite particles dry seed, described method comprises: the zeolite particles of described seed with pre-add moisture contacted, and makes described zeolite particles absorb moisture from described seed.

Description

Method of Drying Seeds

technical field

The present invention relates to a method for improving seed quality. More specifically, the present invention relates to methods for drying seeds using zeolites as moisture absorbing materials.

Background technique

The moisture content of seeds used for sowing or seeds being sown plays a vital role in the quality of these seeds and their degradation control. Although this is a generally accepted fact, the techniques used to dry sown seeds are still largely based on a stream of heated air circulated through the seed pile. Existing dedicated seed drying equipment based on this technology is technologically advanced but expensive. For seeds intended for consumption, quality characteristics must also be preserved in order to preserve taste and nutritional value. For example, for brewing barley it is very important that the germination properties of the seeds are not weakened by eg fungal attack.

An important consideration in seed drying is that the germination ability (germination rate) and longevity (shelf life) of the seeds must be maintained. Germination capacity refers to the percentage of seeds that germinate to develop into full seedlings after a specified period of time under optimal storage conditions. Germination ability was determined using representative seed samples. It has been found that the degree of drying process affects the degree of germination ability, with over-drying often resulting in loss of vigor. However, insufficient drying can lead to molding when the seeds are stored. What's more, each type of seed has its own optimum conditions for drying. It has proven difficult to generate dry conditions that work well for a wide variety of seeds.

Although sowing seeds produced by seed companies are generally of very high quality, the majority of sowing seeds used worldwide are "farm-saved seeds" which vary in quality from season to season. At harvest time, the moisture content of the seed is in most cases not optimal, and the moisture content in the seed pile is often not evenly distributed due to site differences and varying levels of seed maturity on the plants.

Farm saved seed, or "farmer's seed," is usually stored for several months before it is planted. When seeds are stored in countries with high humidity and high temperatures, 80% of the seeds will die or be useless during sowing, and drying is necessary to avoid germination. Much post-harvest loss is due to improper drying and germination of the seeds. Specifically, small farmers need suitable seed drying methods to improve the quality of stored seeds.

There is currently no ready-made method for small farmers in under-industrialized regions of the world to properly dry their farms to preserve seed. Existing airflow dryers are complex and expensive and require a relatively high level of operator skill. Although a central seed treatment facility is available, it is primarily too expensive to transport farm-saved seed for large crops to a central seed treatment facility. It would be more convenient to bring seed treatment facilities to farmers to improve the quality of these seeds. This calls for mobile systems for seed treatment. In principle, such a mobile seed treatment unit should be simple and easy to operate in order to support seed treatment of farm-saved seeds on farms in second and third world countries. Therefore, there is a need for a seed drying system that is simple, cheap, robust, effective yet sufficiently controllable and preferably transportable and preferably even operable during seed transport.

Contents of the invention

The inventors have now developed a simple transportable (removable) seed drying method which is so simple that it can in principle be implemented in buckets. Dried seeds can in principle be kept in the same bucket for storage without separating the seeds from the zeolite.

The invention is based on the use of zeolites, in particular zeolite particles (granules). The problem with such desiccants is that although they can be easily used to extract moisture from other substances, the drying process is extremely stringent, especially when zeolite beads are in direct contact with wet (or high moisture content) products when placed. Zeolite beads have been successfully used in the drying of cooked vegetables and aqueous products such as wastewater sludge, as well as in the roasting of coffee and cocoa beans. However, the plant cells in this product do not need to be alive compared to the germ of the seeds that are sown or used to make beer. Also, seeds intended for consumption or used as a condiment may suffer quality deterioration if the temperature is too high. In fact, the use of zeolites in the drying of sown seeds is still unknown territory. It was therefore not known so far whether it is possible to dry seeds in a very controlled manner and maintain germination capacity in simple (preferably also mobile) and cost-effective equipment based on highly hygroscopic zeolites.

The present inventors have found that drying seeds using zeolites is problematic. In fact, it was found that mixing freshly harvested seeds with completely dry zeolite beads with subsequent absorption of moisture from the seeds by these zeolite beads caused a dramatic increase in the temperature of the mixture due to the heat generated in the zeolite beads. In fact, a lot (high level) of heat is usually generated when the seeds are placed in contact with the zeolite particles. This heating, often exceeding 60-100°C, is extremely detrimental to seed quality.

The inventors have now overcome this problem and have been able to produce dry seeds with high germination capacity and long shelf life. A solution to this problem is provided by mixing the seed with zeolite particles premoisturized to a moisture content of at least 3 wt%. It was found that the initial exothermic moisture uptake of the zeolite was the most damaging, but this heat was largely prevented when the zeolite beads were pre-hydrated to a moisture content of at least 3 wt%. These advantages are that the seeds are not exposed to the heat generated by the zeolite during drying, the germination ability is not affected by this drying method, while the germination ability of the seeds during storage is maintained relative to the prior art drying methods under ambient conditions.

In a first aspect, the present invention provides a method for drying seeds, said method comprising the steps of:

a) mixing the seed with pre-moisturized zeolite particles having a moisture content of at least 3% by weight, preferably at least 5% by weight, more preferably at least 7% by weight, to provide a seed-zeolite mixture, and

b) drying the seeds in the mixture to a moisture content between 2 wt% and 12 wt%.

The seed/zeolite mixture can be prepared by mixing, blending, centrifuging, shaking or tumbling. This can be done automatically using mixers, rotors, blenders, centrifuges, shakers or tumblers. A rotating drum, such as a concrete mixer model, is preferably used.

In a preferred embodiment of the method, the pre-moisturized zeolite particles are pre-moisturized prior to mixing to a moisture content between 5 wt% and 18 wt%, preferably to a moisture content between 15 wt% and 20 wt%.

In a preferred embodiment of the method according to the invention, the pre-moisturized zeolite particles are pre-moisturized to between 15% and 85% by weight of their maximum moisture content, preferably to 20% to 85% by weight of their maximum moisture content, prior to mixing. %, more preferably between 50% and 80t%.

In a preferred embodiment of the method the zeolite particles are particles having a maximum moisture content of 20 wt% to 40 wt%, preferably a maximum moisture content of 25 wt% to 40 wt%.

In a preferred embodiment of the method according to the invention, the final (after drying) moisture content of the seeds is achieved by stopping the drying process. This can be done by calculating the maximum moisture absorption capacity of the zeolite and adding just enough (but not more) zeolite to the mixture to achieve the target seed moisture content. Thus, the final moisture content of the seed can be achieved by mixing the seed and pre-moisturized zeolite particles in a predetermined weight ratio, wherein the moisture uptake weight of the zeolite particles relative to their moisture content before mixing is selected such that all zeolite particles The selected seeds reach their maximum moisture content at the final moisture content.

Alternatively, the final moisture content of the seed can be achieved by separating the seed and zeolite particles at a selected final moisture content of the seed.

In a further alternative embodiment, the final moisture content of the seed can be achieved by freezing the mixture at a selected final moisture content of the seed. For example, freezing can be achieved by lowering the temperature of the mixture to below -5°C or even below -20°C. At these temperatures, no water exchange occurs from the seed to the zeolite particles.

The drying step can also be achieved in multiple steps, from a seed moisture content of 25 wt% down to 20 wt% and in a subsequent step (with fresh pre-moisturized zeolite particles) to a seed moisture content of 15 wt%. It is also possible to add additional pre-moisturized zeolite particles to the dried or drying mixture to achieve a lower moisture content of the seeds. In practice, the step of mixing the seed with the pre-moisturized zeolite particles can be repeated until the moisture content of the seed reaches the desired level.

In another preferred embodiment of the method according to the invention, the seeds are free from water prior to mixing. This means that the seeds are allowed to dry in the air, or air can be blown over the seeds, or the seeds can be rolled over an absorbent pad before adding them to the mix.

It is possible in the method according to the invention to determine the moisture content of the seed before, during and/or after drying, for example by determining the moisture content. Preferably the moisture content of the seed is measured prior to drying to determine the amount of moisture extracted from said seed and thereby determine the amount of pre-moisturized zeolite required to dry the seed.

In a preferred embodiment of the method according to the invention, the mixture obtained after mixing the seeds and zeolite particles is kept in motion. This holding motion can be maintained until the seeds dry out.

It is also possible to separate the seed and zeolite particles after drying, for example by sieving, but in some cases it is possible to keep the seed and zeolite mixed and sow the mixture to produce a crop. For sieving, it is advantageous to choose the zeolite particles such that their average particle size is larger than that of the seeds.

In a preferred embodiment of the invention the seeds are freshly harvested seeds. An advantage of the method of the invention is that this drying can be carried out "on-farm", which term means that the method does not have to be carried out on an industrial scale or in an industrial setting, but can be carried out in a small-scale agricultural setting, most preferably directly on the Harvest the facts of field implementation.

The seeds that can be used in the method according to the invention can in principle be any type of seed, preferably vegetable seeds or fruit seeds, but consumer seeds, forage seeds or seeds of industrial crops can also be treated with the method according to the invention. Very suitable seeds are soybean seeds or rice seeds.

Drying at ambient temperature is possible, but elevated or reduced temperature environments are also possible.

Although the process of the present invention is essentially complete once the seed has been dried to the desired moisture content, it is possible to extend the process with additional steps, such as by regenerating the zeolite particles. Regeneration in this context refers to the process of drying zeolites to prepare them for a new round of seed drying. Zeolite regeneration is specifically performed by heat-treating zeolite particles. The regeneration is preferably carried out at a temperature between 100 and 400°C, more preferably between 200 and 250°C. In a preferred embodiment of the method of the invention, the method may comprise a step of regenerating said zeolite particles by heating, preferably at a temperature between 200 and 400°C, more preferably between 220 and 250°C. The regeneration step is preferably carried out before the pre-moisture step in which the zeolite particles are brought to a moisture content of at least 3 wt%, preferably at least 5 wt%, with water.

In another aspect, the method of the invention relates to the use of zeolite particles for drying seeds.

Description of drawings

Figure 1 shows the device described in Example 1.

FIG. 2 shows the moisture content and temperature in the seed container during and after drying with zeolite particles as described in Example 2. FIG.

Figure 3 shows the effect of storage on the germination capacity of seeds dried by two different methods.

Detailed ways

The term "seed" means any seed, such as: rough seeds, coated seeds, primed seeds, coated seeds. In fact, as stated above, any seed can be used in the methods of the present invention. Particularly useful are the following seeds: wheat, oats, corn (corn), barley, rye, millet, rice, soybean, rapeseed, linseed (flax), sunflower, carrot, black salsify, runner bean (runner bean), goa bean, asparaguspea or winged bean, lentil, vine or rack bean, green beans, fava or devesseled beans, green peas or green peas , lupine, tomato, pepper, melon, squash, cucumber, eggplant, zucchini (zucchini), onion, leek (leek), lettuce (lettuce), endive, spinach, wild lettuce (corn salad) ), gherkins, (red) cabbage, savoy cabbage, pointed cabbage, Chinese cabbage, greens (bok choy), cauliflower, Brussels sprouts (bun kale, Brussels sprouts ), beets, beetroot, kohlrabi, chicory, artichokes, asparagus, broccoli (broccoli), celeriac, celery, radishes, herbs and spices, coriander seeds, peanuts, sesame. Most preferably soybean and rice seeds are used in these aspects of the invention. Seeds include references to seeds for sowing, seeds for consumption (such as rice and wheat), and seeds used as spices (such as coriander seeds). Preferably, the seeds of the aspects of the invention are most advantageously used for sowing seeds and consuming seeds, most preferably for sowing seeds. Roasted seeds may be used in these aspects of the invention, but are preferably excluded from these aspects of the invention. In preferred embodiments of the aspects of the invention, the seeds are fresh seeds. In other preferred embodiments of the invention, the seeds (before drying by the method of the invention) have a moisture content of at least 3 wt%, more preferably at least 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10wt%, 11wt%, 12wt%, 13wt% and 14wt%, or at least 15wt%.

The term "sowing seed" refers to a seed for sowing, ie, a living seed for production of progeny plants grown from said sowing seed when sown in soil or a suitable growing subsoil. The term sowing seeds does not cover powdered seeds not intended for sowing purposes such as ground coffee, flour and cocoa.

The term "zeolite" refers to a family of microporous hydrated aluminosilicate minerals. More than 150 zeolite types have been synthesized and 48 naturally occurring zeolites are known. Zeolites have an "open" structure capable of accommodating a wide variety of cations such as Na ⁺ , K ⁺ , Ca ²⁺ , Mg ²⁺ , etc. These positively charged ions are fairly loosely fixed and can be easily exchanged for other ions in contact solution. Some of the more common inorganic zeolites are: Amicite, Analcime, Barrerite, Bellbergite, Brewsterite, Boggsite , Strontium zeolite, Chabazite, Clinoptilolite, Cowlesite, Cyclone, Barium zeolite, Column zeolite, Erionite, Faujasite, Ferrierite, phillipsite, hydrocalcite, gneline Zeolite, Gobbinsite, Gonnardite, Goosecreekite, Glycine, Herschelite, Heulandite, Labidite, Levyne, Maury Lead zeolite (Maricopaite), needle zeolite, malt potassium zeolite, middle zeolite, montsommaite (Montesommaite), mordenite, sodium zeolite, potassium zeolite (Offretite), paranatrolite (Paranatrolite), alkali zeolite, Pentasil type zeolite (five-membered ring zeolite, Pentasil), sialite (strontium alkali zeolite, Perlialite), phillipsite, cesium zeolite (Pollucite), calcium zeolite, sodium ring crystal zeolite (Sodium Dachiardite), red glow Zeolite (Stellerite), stilbite, tetranatrolite (Tetranatrolite), zeolite, Tschernichite (Tschernichite), clindenite, calciferite, chabazite (Willhendersonite) and Yugawara zeolite (Yugawaralite). All of these zeolites are equally suitable for use in the present invention. An exemplary inorganic formula is: Na ₂ Al ₂ Si ₃ O ₁₀ -2H ₂ O, which is the chemical formula for sodium zeolite. Naturally occurring zeolites are seldom pure, but are altered to varying degrees by contamination with other minerals, metals, quartz, or other zeolites. For this reason, naturally occurring zeolites are less preferred in many applications where homogeneity and purity are important, however such impure zeolites are well suited for this application.

The term zeolite includes references to zeolite granules, zeolite beads and zeolite particles. Examples of commercially available zeolites are: Linde type A (LTA), Linde type X and Y (Al-rich and Si-rich FAU), Silicate-1 and ZSM-5 (MFI ), and Linde (Linde) type B (zeolite P) (GIS). Other commercially available synthetic zeolites include Beta (β) (BEA), Linde type F (EDI), Linde type L (LTL), Linde type W (MER), SSZ-32 (MTT), (clinoptilolite). All are aluminosilicates. In the process of the present invention, Linde (Linde) type A zeolites (NaA, KA, CaA), also referred to by the three-letter code LTA (Linde (Linde) type A) zeolites, or 3A, 4A and/or 5A types are suitable for use.

The size of the zeolite particles used herein is not particularly limited in various aspects of the present invention, but preferably the size of the zeolite particles is larger than the size of the seed, preferably between 1 and 40 mm, more preferably between 5 and 15 mm, still more preferably 5 mm , 6, 7, 8, 10, 11, 12, 13 or 14mm. The advantage of using zeolite particles larger than the seed is related to the ease of separating the zeolite from the seed. It is highly preferred that the zeolite particles have a diameter of 8 mm.

In all cases the zeolites are capable of absorbing water directly or from moisture or from water vapor in the air. Zeolites are capable of retaining up to 55% or more of their weight in water. Depending on the initial moisture content of the seed, the water retention capacity of the zeolite used and the desired final moisture content of the seed, the zeolite can be formulated in a ratio of 100:1 to 1:100, for example, 50:1, 20:1, 15:1, 10:1, 8:1, 6:1, 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:1 8. 1:10, 1:15, 1:20 or 1:50, preferably 3:1 to 1:50 weight ratio (zeolite weight relative to seed weight) is added to the seeds. Where low zeolite levels need to be used (eg, cost considerations), it may be desirable to use zeolite at eg 1:100 to 1:1000 (zeolite weight to seed weight). Low zeolite dosages will generally require longer drying times, or multiple successive drying steps with intermittent regeneration of the zeolite between successive drying steps. The above mentioned desired final seed moisture content (ie after the drying process of the invention) can eg be a moisture content of 3 wt% - 15 wt%, preferably 5 wt% - 10 wt%, more preferably about 8 wt%.

In a preferred method of the invention, zeolite is used to dry the seeds whereby the seeds are in direct physical contact with the zeolite. However, the terms "mixture" and "mixing seeds with pre-moisturized zeolite particles" as used herein should be understood to also cover containers in which the zeolite is placed and containers (each having moisture permeable walls, bags, boxes or boxes) are placed in contact with the seeds (or vice versa). It should be understood that those embodiments in which heat is generated by the zeolite particles due to moisture absorption from the seed, wherein the seed is in such a position relative to the zeolite that said generated heat can damage the quality of the seed are contemplated as an aspect of the present invention, Because they would benefit from the discovery that this damage can be avoided by using pre-moisturized zeolite particles.

Drying can be carried out in an open system, but is preferably carried out in a container. In that way, the influence from moisture present in the atmosphere based on the drying process can be minimized. As used herein, "vessel" refers to any enclosed or semi-enclosed environment suitable for holding seeds, zeolites, or a mixture of both. Examples of containers are, but are not limited to, bulk carrier holds, ship containers, silos (silos), storage rooms, boxes, barrels or bags. The container can be made of any material, preferably such a container is a plastic or steel container.

A very efficient method that the inventors have now found is based on the use of zeolites to dry the seeds.

The method of the present invention involves contacting the seed with the zeolite particles (or placing them in close proximity to allow moisture and heat to be exchanged directly between the seed and the zeolite). This will cause water (moisture) to transfer from the seed to the zeolite. The absorption or absorption of moisture (water) by zeolite is not an equilibrium reaction, but basically irreversible. Moisture is released from the zeolite by regeneration of the zeolite. This method can be very suitable for implementation immediately after the seed is harvested. Essentially a simple concrete mixer or other tumbler can be used, thereby providing a low cost effective seed drying method that can be used by any farmer directly after harvest. Furthermore, this embodiment can be implemented during transport by mixing the seeds and zeolite in a suitable transport container, thus providing a very efficient mobile drying method. This will lead to a strong decrease in seed moisture content. After drying, the seeds can be used directly (for sowing, for consumption, for processing or sale), they can be stored, or they can be dried further until the desired moisture content is reached. The further drying step here is characterized in that the moisture content of the seed after the further drying step is lower than the moisture content after the previous drying step. For example, the first drying step can result in a decrease in the moisture content, for example from 20wt% - 25wt% to 10wt% - 12wt%. A further drying step may then be used to dry the seed moisture content to, for example, 6-8 wt%.

For example, a desired final moisture content suitable for long-term storage without loss of seed quality is 5-12%, preferably 6-10%, more preferably about 8%.

Advantageously, it has been found that there is no limit to the amount of pre-moisturized zeolite that can be added to a batch of seeds, nor the time that the seeds are exposed to or contacted with the pre-moisturized zeolite. It was observed that long-term exposure of seeds to high amounts of zeolites resulted in dry peels but not dry germs. The obtained seeds can germinate normally. Therefore, without wishing to be bound by theory, it is hypothesized that the zeolite is unable to release (detach) the water bound to the germ. There is therefore no danger of over-drying when using zeolites. Therefore, the amount of zeolite can be properly dosed adequately since the chance of overdosing is minimal. However, the amount of zeolite can also be metered to reach the desired dryness level after a certain time. For example, if a zeolite with a water retention capacity of 50wt% is used, 20kg of dry zeolite is required to reduce the moisture content of 1 ton of seeds by 1wt%.

However, it is most important to use pre-moisturized zeolites. Pre-moisturized zeolites are obtained by contacting commercially available (dried) zeolites or regenerated substantially anhydrous zeolites with water or water vapor, such as that present in air. Zeolites can be pre-moisturized by directly contacting them with liquid water, but since this may result in uneven distribution of water within the zeolite, it is preferred that pre-moisture occur in a controlled manner, such as by exposing the zeolite to Air with a certain humidity allows the zeolite particles to absorb moisture from the air. Thus, regenerated zeolites are substantially anhydrous and are to be avoided for use directly in the various aspects of the present invention.

In various aspects of the invention, the moisture content of the seed can be measured before, during and/or after drying, preferably before and after drying. The moisture content can be measured by any method known in the art. Preferably the method is one in which a change in conductivity is determined. Dried seeds have a lower electrical conductivity compared to seeds with high moisture content. The method is easy to use and simple to implement in a low-skilled field, such as a farm field, by personnel with a low degree of training. Alternatively, the moisture content can be determined by removing an aliquot from the seed, measuring the weight, drying the seed in a drying oven (oven) and measuring the weight loss due to drying, thereby providing an indication of the moisture content. measured value.

In a preferred embodiment of the method according to the invention, the moisture content of the seed is determined before it is mixed with the pre-moisturized zeolite and then the target moisture content is determined. The amount of pre-moisturized zeolite is then selected such that the amount of water to be removed from the seed can be absorbed by the zeolite. The amount of zeolite may be limited so that the seed moisture content exceeds its minimum achievable level of about 3-5 wt%, or the zeolite may be added in excess such that the seed moisture content is reduced to a level of about 3-5 wt%. It was especially surprising that at this level the seeds still exhibited a high germination capacity.

After transferring the water to the zeolite, the zeolite can be separated from the dried material. This additional embodiment of the method of the invention can be accomplished using any method known in the art, for example, separation can be achieved by centrifugation. In a preferred embodiment of the invention, said separation is achieved by sieving. The term "sieving" refers to the separation of a mixture of particles of various sizes into two or more fractions by passing the mixture through a sieve of specified mesh size, a net, or other filtering method. Sieving can also be performed using sieving machines well known in the art. In general, sieves separate desired components from unwanted substances. Preferably the seed and zeolite are of different sizes, thereby allowing efficient separation by sieves. Preferably the size of the zeolite particles is larger than the size of the seed. More preferably, the size of the zeolite is chosen such that a complete separation of the zeolite from the seed is possible using a sieve. Preferably, the size of the zeolite particles is between 0.1 and 20 mm, more preferably between 1.5 and 15 mm, even more preferably said size is 6, 7, 8, 9, 10, 11, 12, 13 or 14 mm, most preferably 8 mm . Although it is preferred to separate the dry seeds from the zeolite, the seeds can also be used without separation.

The mixture can remain static, meaning that the seeds and zeolite are added together without any further stirring of the mixture, or the mixture can remain in motion. The mixture can be kept in motion, for example, by using mixers, tumblers, blenders, shakers or tumblers.

In a further embodiment of the invention, the zeolite can be regenerated and reused by heating. Regeneration can be carried out after each drying step of the method of the invention. For example, the zeolite can be regenerated after drying when the zeolite and seeds are separated as described above. Regeneration can be done using any known method, eg via steam, flame heating, via gas, stove heating or microwave ovens can be used. In a preferred embodiment of the present invention, the heating is carried out using a continuous microwave system. The regeneration can be carried out at a temperature between 200 and 400°C, more preferably between 220 and 250°C.

The main advantage of the method of the present invention is that the basic step of improving the storability of seeds can be carried out directly at, or at least close to, the harvesting site, thereby allowing rapid drying of these seeds, which leads to improved storability and quality of said seeds .

Example

Embodiment 1. adopts complete dehydration zeolite to carry out direct drying

The zeolite particles were dried in an oven at 250°C to provide a completely dry zeolite (totally dry zeolite). Dry zeolite particles were mixed with freshly harvested sugar beet (fodder beet, Beta vulgaris, beta vulgaris) seeds in equal weight in containers and the temperature in the containers was monitored. The temperature in the mixture reached a value of 90° C. very quickly.

In a parallel experiment, zeolite particles were mixed with a small volume of water and the temperature in the container was recorded (see Figure 1). The temperature increased almost immediately to values exceeding 80°C.

Considering that temperatures of 40-50°C are lethal or very detrimental to the viability and germination quality of the seeds, it is clear that direct mixing of seeds with whole dry zeolite is not beneficial.

Example 2. Comparison of sun drying and zeolite bead drying

Pepper (Capsicum) seeds were traditionally harvested in Thailand by farmers (members of TVRC - Tropical Vegetable Research Center). 50% of the seeds were dried by the classical method (dried in the sun) and then stored in airtight plastic containers. The remaining 50% of the seeds harvested were dried using the method of the invention using zeolite particles (zeolite bead drying) and the obtained seeds were stored in the same way.

For the classic drying system, sun drying is used (the only system available in Thailand).

For the drying method using zeolite particles, the following method was used: zeolite beads with an average diameter of 8 mm were used. The zeolite beads were dried in an oven at 250° C. for 3 h, after which the zeolite beads had a maximum moisture absorption capacity of 27 wt%. The zeolite beads were then pre-moisturized to a moisture content of 5 wt%, changing the maximum moisture absorption capacity of these zeolite beads to 22 wt%. Mix seeds and zeolite beads and store in an airtight plastic container.

The moisture content of both sun-dried and zeolite bead-dried samples was determined before and after the drying process. A total of 4 replicates were performed and the official ISTA (International Seed Testing Association) method was used to determine moisture content.

The following results were obtained: Before drying, the seeds had a moisture content of 24 wt% (dry extraction method). After drying and during storage, the measured moisture content is shown in Table 1.

Table 1. Moisture content (in wt% of water) of seeds dried by two different methods.

In a sealed container of zeolite bead dried seeds, the relative air humidity was recorded during storage. The fact that the relative humidity (rH) increased over the period of months indicated that the zeolite beads had reached their maximum water uptake capacity, i.e., the water uptake capacity had been completely exhausted and the air in the container had reached equilibrium with the residual water in the seeds. (See Figure 2).

The mass difference between the two samples is significant. Table 2 summarizes some results. Germination was determined by the ISTA prescribed method indicated above under controlled laboratory conditions. Soil emergence was also tested, as was the weight of the plantlets after 20 days.

Table 2. Germination (in % of germinated seeds) and emergence (in % of emerging seeds) of seeds dried by two different methods and subsequently stored as described above.

sun dried Zeolite bead drying Germination rate immediately after drying (%) 92.9 91.2 Germination rate after 6 months (%) 29.5 86.4 Unearthed rate after 6 months (%) 54.8 88.1 Seedling weight (in grams) after 20 days 1.74 2.22

As can be seen in Figure 3, germination immediately after drying was better for both methods. However, the zeolite bead drying method provided far better results after 6 months storage in a sealed container.

in conclusion

If the zeolite beads are pre-moisturized, the negative influence of the exothermic reaction of the zeolite beads can be avoided and the seeds can be dried in a very simple manner. The drying method of the invention has such a critical effect that the quality (eg germination ability) of these seeds remains very high after storage. Additionally, seeds dried in this manner exhibited increased field emergence and more vigorous growth. This improves the health and subsequent yield of plants grown from these seeds. Additionally it would be expected that properly dried seeds would be less attacked by fungi.

Claims (17)

1., for a method for drying sowing seed, said method comprising the steps of:

A) seed is mixed with the zeolite particles with the moisture at least pre-add moisture of 3wt% and provides seed-zeolite mixture, and

B) make described seed in described mixture, be dried to final moisture content between 2wt% to 12wt%.

2. method according to claim 1, wherein before mixing by the moisture between the zeolite particles pre-add moisture to 5wt% to 18wt% of described pre-add moisture.

3. method according to claim 1, wherein before mixing by the moisture between the zeolite particles pre-add moisture to 15wt% to 20wt% of described pre-add moisture.

4. the method according to any one of claim 1-3, wherein before mixing by the zeolite particles pre-add moisture of described pre-add moisture to its maximum moisture absorbing capacity 15% to 85% between.

5. the method according to any one of claim 1-3, wherein before mixing by the zeolite particles pre-add moisture of described pre-add moisture to its maximum moisture absorbing capacity 50% to 80% between.

6. the method according to any one of claim 1-3, wherein said zeolite particles has the maximum moisture absorbing capacity of 20wt%-40wt%.

7. the method according to any one of claim 1-3, the described final moisture content of wherein said seed reaches in the following manner

-zeolite particles of seed and pre-add moisture is mixed according to predetermined weight ratio, wherein, select described zeolite particles relative to the moisture absorption weight of moisture before its mixing, be issued to its maximum moisture absorbing capacity to make all zeolite particles at selected final seed moisture content content;

-seed is separated under selected final seed moisture content content with zeolite particles, or

-under selected final seed moisture content content by freezing for described mixture.

8. the method according to any one of claim 1-3, wherein said seed is before mixing containing adhering to water.

9. the method according to any one of claim 1-3, the described moisture of wherein said seed measures before the drying and afterwards.

10. the method according to any one of claim 1-3, after wherein being mixed with zeolite particles by seed, makes described mixture keep motion.

11. methods according to any one of claim 1-3, wherein said seed is separated after drying with zeolite particles.

12. methods according to any one of claim 1-3, wherein said seed is the seed of new results.

13. methods according to any one of claim 1-3, wherein said seed is paddy seeds or soya seeds.

14. methods according to any one of claim 1-3, comprise the step regenerating described zeolite particles by heating further.

15. methods according to any one of claim 1-3, comprise the step being regenerated described zeolite particles by heating at the temperature between 200-400 DEG C further.

16. methods according to any one of claim 1-3, comprise the step being regenerated described zeolite particles by heating at the temperature between 220-250 DEG C further.

The zeolite particles of 17. pre-add moisture is used for the purposes of dry sowing seed.